Composition and Method for Improving the Production of Petroleum Hydrocarbons

ABSTRACT

A novel surfactant composition that comprises of two surfactant components, a solvent, and water. The surfactant composition is added to a fracturing fluid, which is then pumped downhole into a subterranean formation where the novel characteristics of the fracturing fluid lend to improved oil production over the fracturing fluid without the surfactant composition.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of and claims the benefit of U.S. Pat.Application No. 16/948,368, titled “Composition and Method for Improvingthe Production of Petroleum Hydrocarbons,” filed Sep. 15, 2020, now U.S.Pat. No. 11,499,091, issued Nov. 15, 2022, the full disclosure of whichis hereby incorporated by reference in its entirety for all intents andpurposes.

FIELD

The disclosure relates generally to the oil and gas industry. Thedisclosure relates specifically to a fracturing fluid additive.

BACKGROUND

A fracturing fluid can be a water-based composition of several chemicaladditives with proppant, that is pumped into a subterranean formationand partially returns to the surface. It would be advantageous to employa surfactant additive that is thermal and hydrolytically stable at hightemperature, is tolerant of water of high salinity and hardness, andcould change the wettability of subterranean formations from oil-wet towater-wet in order to increase the oil recovery of the formation.

SUMMARY

In an embodiment, the surfactant solution is a mixture of a firstsurfactant, a second surfactant, a solvent, and water. In an embodiment,the first surfactant is an ether sulfonate (anionic surfactant) havingthe formula R₁O(R₂O)_(x)(R₃O)_(y)CH₂CH(OH)CH₂SO₃M, where R₁ is a linearor branched alkyl group having 5 to 30 carbon atoms, R₂ is —CH₂CH₂—, R₃is —CH(CH₃)CH₂—, x is an integer from 2 to 30, y is an integer from 0 to20, and M is a monovalent cation including, but not limited to, sodium,lithium, potassium or ammonium. In an embodiment, the concentration ofthe first surfactant in the surfactant solution is from about 1 wt.% to65 wt.%. In an embodiment, the concentration of the first surfactant inthe surfactant solution is from about 5 wt.% to 55 wt.%. In anembodiment, the concentration of the first surfactant in the surfactantsolution is from about 10 wt.% to 45 wt.%.

In an embodiment, the second surfactant is an alkyl alkoxylated nonionicsurfactant having the formula R₄O(R₂O)_(m)(R₃O)_(n)H, where R₄ is alinear or branched alkyl group having 5 to 30 carbon atoms, m is aninteger from 5 to 30, and n is an integer from 1 to 20. In anembodiment, the concentration of the second surfactant in the surfactantsolution is from about 1 wt.% to 80 wt.%. In an embodiment, theconcentration of the second surfactant in the surfactant solution isfrom about 15 wt.% to 65 wt.%. In an embodiment, the concentration ofthe second surfactant in the surfactant solution is from about 30 wt.%to 50 wt.%.

In an embodiment, the solvent is at least one or any combination of thesolvents including, but not limited to, methanol, ethanol, isopropanol,1-propanol, butanol, acetone, ethyl lactate, glycerol, ethylene glycol,ethylene glycol butyl ether, butyl acetate, and acetic acid. In anembodiment, the solvent is one or any combination of solvents known toone of ordinary skill in the art for use in a wellbore. In anembodiment, the concentration of the solvent in the surfactant solutionis from about 1 wt.% to 90 wt.%. In an embodiment, the concentration ofthe solvent in the surfactant solution is from about 5 wt.% to 50 wt.%.In an embodiment, the concentration of the solvent in the surfactantsolution is from about 10 wt.% to 35 wt.%.

In an embodiment, the concentration of water in the surfactant solutionis from about 1 wt.% to 90 wt.%. In an embodiment, the concentration ofwater in the surfactant solution is from about 15 wt.% to 60 wt.%. In anembodiment, the concentration of water in the surfactant solution isfrom about 30 wt.% to 45 wt.%.

In an embodiment, a method for using the surfactant solution includesmixing the surfactant solution into the fracturing fluids to form afracturing fluid composition and pumping the fracturing fluidcomposition into a well bore at a flow rate and a pressure sufficient tofracture the subterranean formation. In an embodiment, the concentrationof the surfactant solution in the fracturing fluid is from about 0.02 to50 gpt (gallon per thousand gallons). In an embodiment, theconcentration of the surfactant solution in the fracturing fluid is fromabout 0.1 gpt to 10 gpt. In an embodiment, the concentration of thesurfactant solution in the fracturing fluids is from about 0.5 gpt to 2gpt. In an embodiment, the fracturing fluid can be a linear gel, acrosslinked gel, or a slickwater. In an embodiment, a gelling agent canbe present in the fracturing fluids. In an embodiment, the gelling agentcan be hydroxyethyl guar, carboxymethyl guar, hydroxypropyl guar,carboxymethylhydroxypropyl guar, carboxymethylhydroxyethyl guar,carboxyethylcellulose, hydroxyethyl cellulose,carboxymethylhydroxyethylcellulose, carboxymethylcellulose, xanthan,diutan, or any combination thereof. In an embodiment, the fracturingfluids can contain other components including, but not limited to,proppants, biocides, scale inhibitors, clay stabilizers, frictionreducers, crosslinking agents, breakers, thermal stabilizers, a pHadjustor, a corrosion inhibitor, an iron control agent, or anycombination thereof.

In an embodiment, the surfactant solution can be present in fracturingfluids used as a wettability altering agent to improve or increase theproduction of petroleum hydrocarbons from high temperature subterraneanformations with connate water of high salinity and hardness. Thesurfactant solution disclosed herein is a novel composition and hasseveral advantages over previous surfactant solutions. The surfactantsolution is thermally and hydrolytically stable at a high temperature,is tolerant to connate water of high salinity and hardness, can changethe wettability of subterranean formation from oil-wet to water-wet, andimproves oil recovery.

The foregoing has outlined rather broadly the features of the presentdisclosure in order that the detailed description that follows may bebetter understood. Additional features and advantages of the disclosurewill be described hereinafter, which form the subject of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and otherenhancements and objects of the disclosure are obtained, a moreparticular description of the disclosure briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the disclosure and are therefore notto be considered limiting of its scope, the disclosure will be describedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 depicts a photo of the contact angle of a single 5 µL drop ofBrine #1 without surfactant that was placed on a Parker sandstone corethat had been saturated with crude oil and aged at 176° F. for threeweeks;

FIG. 2 depicts a photo of the contact angle of a single 5 µL drop ofBrine #1 with 1 gpt surfactant solution #1 that was placed on a Parkersandstone core that had been saturated with crude oil and aged at 176°F. for three weeks;

FIG. 3 depicts a photo of the contact angle of a single 5 µL drop ofBrine #1 with 1 gpt surfactant solution #2 that was placed on a Parkersandstone core that had been saturated with crude oil and aged at 176°F. for three weeks;

FIG. 4 depicts a photo of the contact angle of a single 5 µL drop ofBrine #1 with 1 gpt surfactant solution #3 that was placed on a Parkersandstone core that had been saturated with crude oil and aged at 176°F. for three weeks;

FIG. 5 depicts a graph of interfacial tensions (IFT) that were measuredbetween crude oil and Brine #1 with 1 gpt surfactant solution #1 ( agedand unaged at 320° F. for four days) . The temperature was increasedfrom room temperature to 176° F., and then was maintained at 176° F. forover 1.5 hours during the IFT measurement;

FIG. 6 depicts a graph of interfacial tensions that were measuredbetween crude oil and Brine #1, crude oil and Brine #2, crude oil andBrine #3, crude oil and Brine #4, each with 1 gpt Surfactant Solution#1.

FIG. 7 depicts a graph of interfacial tensions that were measuredbetween crude oil and Brine #2 and crude oil and Brine #5, each with 1gpt Surfactant Solution #1.

FIG. 8 depicts a graph of cumulative oil recovery rates of thespontaneous imbibition tests at 176° F. for Brine #1 with and without 1gpt surfactant solution #1.

DETAILED DESCRIPTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the preferred embodiments of the presentdisclosure only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of various embodiments of thedisclosure. In this regard, no attempt is made to show structuraldetails of the disclosure in more detail than is necessary for thefundamental understanding of the disclosure, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the disclosure may be embodied in practice.

The following definitions and explanations are meant and intended to becontrolling in any future construction unless clearly and unambiguouslymodified in the following examples or when application of the meaningrenders any construction meaningless or essentially meaningless. Incases where the construction of the term would render it meaningless oressentially meaningless, the definition should be taken from Webster’sDictionary 3 ^(rd) Edition.

Anionic Surfactants, Nonionic Surfactants, and Solvents AnionicSurfactants #1-3

The ether sulfonate (anionic surfactants) tested herein have thefollowing formula:

-   R₁O(R₂O)_(x)(R₃O)_(y)CH₂CH(OH)CH₂SO₃M.    -   Where R₁ is C₁₁ to C₁₄ iso-alkyl, R₂ is ethyl, and R₃ is propyl        with structure of CH(CH₃)CH₂.    -   Anionic surfactant #1: x=9 and y=4;    -   Anionic surfactant #2: x=9 and y=12;    -   Anionic surfactant #3: x=18 and y=0.

Nonionic Surfactants #1-3

The alkyl alkoxylated nonionic surfactants tested herein have thefollowing formula:

-   R₄O(R₂O)_(m)(R₃O)_(n)H    -   Where R4 is C₁₁ to C₁₄ iso-alkyl. R₂ is ethyl, R₃ is propyl with        structure of CH(CH₃)CH₂.    -   Nonionic #1: m=18 and n=1;    -   Nonionic #2: m=9 and n=4;    -   Nonionic #3: m=9 and n=12.

Solvents

In an embodiment, the solvent is at least one or any combination of thesolvents including, but not limited to, methanol, ethanol, isopropanol,1-propanol, butanol, acetone, ethyl lactate, glycerol, ethylene glycol,ethylene glycol butyl ether, butyl acetate, and acetic acid. In anembodiment, the solvent is one or any combination of solvents known toone of ordinary skill in the art for use in a wellbore.

In an embodiment, ethylene glycol butyl ether can be used as a solventin the surfactant solution. Ethylene glycol butyl ether (Solvent #1)tested herein has the following structure:

-   CH₃CH₂CH₂CH₂OCH₂CH₂OH

Surfactant Solutions

In an embodiment, various surfactant solutions were made by combining ananionic surfactant, a nonionic surfactant, a solvent, and water.

Table 1 Surfactant Solutions #1-3 Surfactant solution #1 Surfactantsolution #2 Surfactant solution #3 Anionic #1: 13.0 wt. % Anionic #2:13.0 wt. % Anionic #3: 14.8 wt. % Nonionic #1: 43.0 wt. % Nonionic #2:35.2 wt. % Nonionic #3: 34.2 wt. % Solvent #1: 11.4 wt. % Solvent #1:9.3 wt. % Solvent #1: 9.2 wt. % Water: 32.6 wt. % Water: 42.5 wt. %Water: 41.8 wt. %

Brines

In an embodiment, various brines were made by mixing sodium chloride andcalcium chloride in deionized water. In an embodiment, a brine cancontain one or more of sodium chloride, calcium chloride, potassiumchloride, magnesium chloride, sodium sulfate, and potassium sulfate.

Table 2 Brines #1-5 Brine #1 Brine #2 Brine #3 Brine #4 Brine #5 NaCl(wt %) 3.0 10.0 15.0 20.0 10.0 CaCl₂ (wt%) 0.5 0.5 0.5 0.5 2.0

Example 1. Wettability Tests

As illustrated in FIG. 1 , FIG. 2 , FIG. 3 , and FIG. 4 , a single dropof brine #1 of 5 µL with and without adding surfactant solutions wasplaced on Parker sandstone cores which had been saturated with crude oilwith an API gravity of 41.7 degrees and aged at 176° F. for 3 weeks. ForFIG. 1 , FIG. 2 , FIG. 3 , and FIG. 4 , the drops of brine #1 werewithout adding any surfactant solution, with 1 gpt surfactant solution#1, with 1 gpt surfactant solution #2, and with 1 gpt surfactantsolution #3, respectively. As illustrated in FIG. 1 , FIG. 2 , FIG. 3 ,and FIG. 4 , the contact angles measured were 117°, 73°, 67°, and 72°,respectively, which indicates that the surfactant solutions changed thewettability of the core surfaces from oil-wet (contact angle > 90°) towater-wet (contact angle <90°).

Example 2. Thermal Stability Tests

Thermal stability of the surfactant solutions was tested by comparingthe interfacial tensions of the surfactant solutions both aged andunaged at 320° F. for 4 days with a “KRUSS spinning drop tensiometerSDT”. The interfacial tensions were measured between Brine #1 with 1 gptsurfactant solution #1 and crude oil with an API gravity of 41.7 degreesas the temperature increased from room temperature to 176° F. andmaintained at 176° F. FIG. 5 shows the curves of the interfacial tensionvs. time for the surfactant both aged and unaged are almost overlappedwhich indicates the surfactant is quite thermally stable at 320° F.

Example 3. Salinity and Hardness Compatibility Tests

The salinity and hardness compatibility of the surfactant solutions wastested by measuring the interfacial tensions between crude oil and brinewith 1 gpt surfactant solutions and different salinity and hardness. TheAPI gravity of the crude oil is 41.7 degrees. FIG. 6 and FIG. 7 show theinterfacial tension of the crude oil with Brine #1, Brine #2, Brine #3,Brine #4, or Brine #5 with 1 gpt surfactant solution #1. Various Brineshave different salinity and hardness. FIG. 6 shows, as the concentrationof sodium chloride increases, the interfacial tension decreases whichindicates the surfactant solution is compatible with high salinity. FIG.7 shows, as the concentration of calcium chloride increases from 0.5 wt.% (Brine #2) to 2.0 wt. % (Brine #5), the interfacial tension slightlydecreases which indicates the surfactant solution is compatible withhigh hardness.

Example 4. Oil Recovery Tests

Spontaneous imbibition tests were used to evaluate the performance ofthe surfactant solutions on improving and increasing oil recovery.Parker sandstone cores with porosity and permeability about 14% and 6 mdrespectively were used for the spontaneous imbibition tests. The coreswere dried for 24 hours at 176° F., saturated with crude oil with an APIgravity of 41.7°, aged at 176° F. for 3 weeks, and then used for thespontaneous imbibition tests. FIG. 8 shows the cumulative oil recoveryrates of the spontaneous imbibition tests at 176° F. for Brine #1 withand without 1 gpt surfactant solution #1. The final oil recovery ratesare 40.4 %OOIP and 28.4 %OOIP for the brine with and without surfactantsolution, respectively. OOIP stands for original oil-in-place.

All of the compositions and methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While the compositions and methods of this disclosure havebeen described in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to thecompositions and methods and in the steps or in the sequence of steps ofthe methods described herein without departing from the concept, spiritand scope of the disclosure. More specifically, it will be apparent thatcertain agents which are both chemically related may be substituted forthe agents described herein while the same or similar results would beachieved. All such similar substitutes and modifications apparent tothose skilled in the art are deemed to be within the spirit, scope andconcept of the disclosure as defined by the appended claims.

What is claimed is:
 1. A method of increasing the production ofpetroleum hydrocarbons comprising: formulating a surfactant solution;mixing the surfactant solution with a fracturing fluid to form afracturing fluid composition; injecting the fracturing fluid compositioninto a well bore at a flow rate and pressure sufficient to fracture thesubterranean formation; wherein the surfactant solution comprises afirst surfactant, a second surfactant, a solvent, and water; and whereinthe production of petroleum hydrocarbons from the well bore is increasedin comparison to production of petroleum hydrocarbons if the surfactantsolution was not added to the fracturing fluid composition.
 2. Themethod of claim 1 wherein the surfactant solution is mixed with thefracturing fluid to a concentration of 0.02 to 50 gallon per thousandgallons of the fracturing fluid.
 3. The method of claim 1: wherein thefirst surfactant is an ether sulfonate having the formula:R₁O(R₂O)_(x)(R₃O)_(y)CH₂CH(OH)CH₂SO₃M, wherein R₁ is a linear orbranched alkyl group having 5 to 30 carbon atoms, R₂ is —CH₂CH₂—, R₃ is—CH(CH₃)CH₂—, x is an integer from 2 to 30, y is an integer from 0 to20, and M is a monovalent cation; wherein the second surfactant is analkyl alkoxylated nonionic surfactant having the formulaR₄)O(R₂O)_(m)(R₃O)_(n)H, where R₄ is a linear or branched alkyl grouphaving 5 to 30 carbon atoms, m is an integer from 5 to 30, and n is aninteger from 1 to 20; and wherein the solvent is methanol, ethanol,isopropanol, 1-propanol, butanol, acetone, ethyl lactate, glycerol,ethylene glycol, ethylene glycol butyl ether, butyl acetate, aceticacid, or any combination thereof.
 4. The method of claim 3 wherein thefracturing fluid composition further comprises a gelling agent, aproppant, a biocide, a scale inhibitor, a clay stabilizer, a frictionreducer, a crosslinking agent, a breaker, a thermal stabilizer, a pHadjuster, a corrosion inhibitor, an iron control agent, or anycombination thereof.
 5. The method of claim 4 wherein the gelling agentis selected from the group comprising: hydroxyethyl guar, carboxymethylguar, hydroxypropyl guar, carboxymethylhydroxypropyl guar,carboxymethylhydroxyethyl guar, carboxyethylcellulose,hydroxyethylcellulose, carboxymethylhydroxyethylcellulose, carboxymethylcellulose,xanthan, diutan, or any combination thereof.